Catalysts for producing high trans-polybutadiene

ABSTRACT

1,3-Butadiene is polymerized to produce a high transpolybutadiene employing a three-component catalyst system comprising: (1) a reducing agent in an oxyether solution; (2) a titanium halide plus molecular iodine wherein the halide is chloride or bromide, or titanium tetraiodide; and (3) a thioether.

United States Patent [191 Naylor Dec. 16, 1975 CATALYSTS FOR PRODUCING HIGH 3,196,143 7/1965 Stewart et al. 260/943 TRANS.P()LYBUTADIENE 3,223,694 12/1965 Farrar 260/943 [75] Inventor: Floyd E. Naylor, Bartlesville, Okla. [73] Assignee: Phillips Petroleum Company, Pnmary Exammerwflham Hamrock Bartlesville, Okla.

22 F lled Mar 1, 1974 ABSTRACT [21] Appl. No.: 447,201

-' 1,3-Butadiene is polymerized to produce a high trans- [52] US CL 260/94 260/94 252/429 B polybutadiene employing a three-component catalyst [51] Int G2 6 1/14 system comprising: (1) a reduclng agent 1n an oxyether solution; (2) a titanium halide plus molecular [58] Fleld of Search 260/943 252/429 B iodine wherein the halide is chloride or bromide, or [56] References Cited titanium tetraiodide; and (3) a thioether.

UNITED STATES PATENTS 6 Claims No Drawings 3,050,513 8/1962 Zelinski et al. 260/943 CATALYSTS FOR PRODUCING HIGH TRANS-POLYBUTADIENE BACKGROUND The invention relates to a method and a catalyst for producing high trans-polybutadiene.

Polymerization of dienes, such as 1,3-butadiene, using catalysts chosen to produce either cisor transpolybutadiene has proven to be an important technique for controlling the properties of such polymers. In general, the higher the trans content of a polybutadiene, the more resinous it is. High trans-polybutadiene is an elastic, tough, crystalline, thermoplastic solid. It is characteristically resistant to attack by ozone and other chemical agents, such as strong acids and bases. High trans-polymers of butadiene are used typically, in fabricating insulation for electrical wires and cables, battery cases, and golf ball covers.

It is an object of the invention to produce polymers.

Another object of the invention is to produce polymers of l,3-butadiene.

Another object of the invention is to produce high trans-polybutadiene.

Still another object of the invention is to provide a novel catalyst for the production of high transpolybutadiene.

Other objects, aspects, and advantages of the invention will become apparent to those skilled in the art upon studying the specification and the appended claims.

SUMMARY In accordance with the invention a high transpolybutadiene is produced by polymerizing l,3-butadione in the presence of a novel catalyst comprising: (1) an oxyether solution of a reducing agent represented by the general formula XMH wherein X is a metal selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium, and M is an element selected from the group consisting of aluminum and boron; (2) a halide of titanium mixed with molecular iodine when the halide is chloride or bromide, or titanium tetraiodide; and (3) a thioether.

DETAILED DESCRIPTION OF THE INVENTION The reducing agent employed in the catalyst system of the present invention is represented by the general formula XMH, wherein X is lithium, sodium, potassium, rubidium, or cesium, and M is aluminum or boron. Some examples of suitable reducing agents are lithium aluminum hydride, sodium borohydride, and potassium aluminum hydride.

The reducing agent is dissolved in an oxyether. Ethers suitable for preparing the solutions include dialkyl ethers such as diethyl ether, di-n-butyl ether, methyl ethyl ether, and methyl-n-amyl ether.

The titanium halide component of the catalyst system is a mixture of either titanium tetrachloride and molecular iodine or titanium tetrabromide and molecular iodine, or alternatively titanium tetraiodide can be used with or without the presence of molecular iodine.

The thioethers suitable for use in the invention are represented by the general formula RSR' wherein R and R are hydrocarbon radicals selected from the group consisting of alkyl and cycloalkyl radicals containing from about 1 to 12 carbon atoms, or,

alternatively, R and R are alkylene groups joined to the sulfur atom and to each other to form a saturated heterocyclic thioether containing from about 4 to 10 carbon atoms. Some examples of suitable thioethers include dimethyl sulfide, diethyl sulfide, methyl ethyl sulfide, tetrahydrothiophene, and dicyclohexyl sulfide. Mixtures of thioethers can also be used.

The catalyst composition, on a mole ratio basis, can vary widely. The mole ratio of'thioether to reducing agent can vary in the range of from about 0.1:] to 100:1, preferably from about 1:1 to 50:1. The mole ratio of reducing agent to titanium halide component can vary in the range of from about 1:1 to 6:1, preferably in the range of from about 1.511 to 5:1. The mole ratio of molecular iodine to titanium tetrachloride or titanium tetrabromide is in the range of from about 0.5:1 to 5:1, preferably in the range of from about 1:1 to 3:1.

Generally the reaction mixture contains a diluent. Diluents suitable for use in the process are hydrocarbons which are not detrimental to the polymerization process. Suitable diluents include paraffinic and cycloparaffinic hydrocarbons and mixtures thereof. Examples of such diluents include n-hexane, n-heptane, 2,2,4-trimethylpentane, and cyclohexane.

The polymerization temperature can vary widely, but usually it is in the range of from about 0 to 100C, preferably from about 30 to C. Also the polymerization pressure varies widely. The polymerization reaction can be carried out under autogenous pressure or at any suitable pressure sufficient to maintain the reaction mixture substantially in the liquid phase. Generally the pressure will thus depend upon the particular diluent being employed and the temperature at which the polymerization is carried out. However, higher pressures can be employed if desired by using a suitable method such as the pressurization of the reactor with a gas which is inert with respect to the polymerization reaction.

Various materials are known to be detrimental to the catalyst of this invention. These materials include carbon dioxide, oxygen and water. It is usually desirable, therefore, that the reactants and catalysts be freed of these materials as well as other materials which may tend to inactivate the catalyst. Furthermore, it is desirable to remove air and moisture from the reaction vessel in which the polymerization is to be conducted. Upon completion of the polymerization, the polymerization mixture is then treated to inactivate the catalyst and to recover the polymer. A suitable method for accomplishing this result involves steam stripping the diluent from the polymer. In another suitable method a catalyst-inactivating material, such as an alcohol, is added to the mixture so as to inactivate the catalyst and cause precipitation of the polymer. The polymer is then separated from the alcohol and diluent by any suitable means, such as decantation or filtration. It has been found to be advantageous to add an antioxidant, such as 2,6-di-t-butyl-4-methylphenol to the polymer solution prior to recovery of the polymer.

ILLUSTRATIVE EXAMPLES The polymerizations were carried out under nitrogen is capped beverage bottles employing anhydrous reactants and conditions. The bottles were tumbled in a constant temperature bath for the stipulated polymerization times and at the stipulated temperatures. Following polymerization, 2,6-di-t-butyl-4-methylphenol EXAMPLES ll 4 A series of examples was made in accordance with the following recipe. The results are shown below. A dash in the table below and the tables that follow indicates no value was determined.

Recipe p.h.m.

Butadiene 100 n-Hexane 660 Diethyl Ether variable Dimethyl sulfide variable Tetrahydrothiophene variable Lithium aluminum hydride (0.4M in diethyl ether) 1.8 mhm Titanium tetrachloride .72 mhm lodine 1.4 mhm Temperature. C 50 Time. hours 5 Charge Order: Hexane. N purge, thioether, LiAlH in diethyl ether solution. TiCl l. but-adiene Diethyl Dimethyl Tetrahydro- Ex. Ether Sulfide thiophene Conv. Trans Vinyl lnh. No. Partsv mhm mhm mhm Wt. Wt. 71 Wt. 72 Visc.

l 2.5 33.8 0 65 83.6 2 7 2.l6 2 5.0 67.6 0 O 55 3 7.5 101.4 0 O 50 4 10.0 135.2 0 O 40 92.0 2.3 1.29 5 2.5 33.8 2 O 80 87.0 2.6 1.60 6 2.5 33.8 4 0 80 91.0 2.4 1.30 7 2.5 33.8 6 0 65 8 2.5 33.8 8 O 75 94.2 2.7 0.90 9 2.5 33.8 0 2 65 89.8 2.8 1.53 10 2.5 33.8 0 4 75 91.3 2.2 1.41 l l 2.5 33.8 0 6 75 12 2.5 33.8 0 8 75 94.3 2.6 0.71 13* 2.5 33.8 0 O 95 83.0 2.5 2.59 14 2.5 33.8 60 0 95.2 3.3 0.74

*These examples were allowed to proceed for a 68-hour polymerization period and in Example 14 the thioether- LiAlH charge order shown above was reversed.

produced were thermoplastic in character.

Shown immediately below are definitions of abbreviations and terms employed in the following working 40 examples. Also included are descriptions and references for analytical and evaluation methods employed.

m.p. Melting point, C

f.p. Freezing point, C

m.h.m. Gram millimoles per hundred grams monomer p.h.m. Parts by weight per 100 parts by weight monomer a. Inherent Viscosity (Inh. Visc.) was determined using tetrahydrofuran instead of toluene by the analyzer employing a differential scanning calorimeter cell. The point of maximum deflection of the endotherm or exotherm under a nitrogen atmosphere was observed. Heating and cooling rates employed were each 10 per minute. Samples were of approximately 15 mg.

c. Polymer microstructure, i.e., trans and vinyl contents were determined by infrared absorption spectroscopy.

Example I, employing no thioether and only that amount of diethyl ether required as solvent for the lithium aluminum hydride employed, constituted a control run which indicated the trans level obtained by the use of that amount of ether which was introduced simply as the solvent for the lithium aluminum hydride. The trend in conversion values for experiments l-3 showed the marked depressive effect on conversion by increasing quantities of diethyl ether. Example 4, employing no thioether but employing a radically high amount of diethyl ether, indicated a good trans value (92 percent), but at the cost of suppressing conversion to only 40 percent. This example showed that increasing the diethyl ether level will ultimately produce high trans values, but at the expense of providing very low polymer yields. Example 8 indicated a good trans value coupled with a good conversion by employing an amount of thioether that was modest in comparison to the amount of diethyl ether present as the solvent for the lithium aluminum hydride. Note, the same quantity of oxyether (diethyl ether) was present in Example 8 as was employed in Example 1 above. Example 12, illtls' trating the use of a cyclic thioether, tetrahydrothiophene, provided a result effectively identical to that in Example 8. It is important to note in these examples that the use of thioethers made it possible to obtain high trans values without incurring substantial suppression of monomer conversion. It is also noted Example 13 involves a longer reaction time than Example 1 and. hence, a superior yield. Example 14 reflected the use of an excessive amount of thioether which produced a very good trans value but a low monomer conversion. This example is not intended as good illustration of the invention, but simply indicates the result of employing excessive amounts of thioether.

EXAMPLE Examples 16-30 demonstrated that a wide variety of titanium tetrachloride and molecular iodine levels can be employed.

EXAMPLES 31-37 A sample of very high trans-polybutadiene was pre- 5 pared in accordance with the following recipe. In accordance with the following recipe, several runs Recipe were made employing lithium aluminum hydride in an oxyether solution, titanium tetraiodide, and a thioether (dimethyl sulfide). Butadiene 100 10 n-Hexane 660 Reclpe Dimethyl sulfide l6 mhm p h m Lithium aluminum hydride (0.55M l in diethyl ether) 1.0 mhm Butadiene Titanium tetrachloride 0.5 mhm n-Hexane 660 Iod1ne I o L0 m. l 5 Dimethyl sulfide variable TFmPermure' C 50 Titanium tetraiodide variable Tlmei hours 7 I v 6 Lithium aluminum hydride (0.45M in Charge Order: n-Hexanc, N2 purge, CHI-SCH, LIAIH4 diethy] ether) L3 mhm f Temperature, C 70 butadlcne Time. hours 3 Charge Order: n-Hexanc. Til LiAlI'L. (CH3)2S. butadiene Ex. 7 B 0 Me s TiI Conv. Trans Vinyl Inh.

After polymerization, 1 part 2,6-d1-tert-butyl-4-- '7 i methylphenol by weight per 100 parts by weight poly- 8 :5 mer was added to the polymer.-Conversion was 70 33 2.5 2.0 "1.2 Trace 34- 2.5 8.0 1.2 7 percent 35 2.5 I 5.0 2.0 32 44.8 30.7 9

36 2.5 8.0 2.0 43 51.8 28.0 128 I 37 2.5 12.0 2.0 63 66.9 17.4 4 Percenttrans (by infrared) 97.4 Percent vinyl (by infrared) 3.2 Inherent viscosity L22 u DTA. m.p. I 1 14C It is probable that proportionally low titanium tetrai- C odide levelswere responsible for. the poor results in Examples 31-34. Runs -37 exhibited the expected 1 v 7 increase in trans content accompanying an increase in is example produced a polymer with an excellent thioether leveL trans value and a good conversion.

EXAMPLES 38-43 EXAMPLES l6.30 35 1 g Examples 38-43 illustrated the use of lithium alumi- In accordance wlth the P @Senes of num hydride in a oxyether solution, titanium tetrachloexflmples was made q m l Pm alummum ride, molecular iodine, and diphenyl sulfide. These runs drlde 1n an oxyether-solution, titanium tetrachl0 were made in accordance with the following recipe. and molecular iodine with dlethyl sulfide as the thloether. Various titanium tetrachloride and molecular iodine levels were employed. 1

Recipe p.h.m.

Butadiene 100 n-Hexane 660 Diethyl sulfide variable Lithium aluminum hydride (0.41M in diethyl ether) l.3 mhm Titanium tetrachloride variable Iodine variable Temperature, "C Time. hours 4 Charge Order: n-Hexane. N- purge,-LiAlH solution,

v (C2H,-,)2S. TiCl I butadiene Ex. TiCl Iodine (C2H5)2S Conv.. Trans Vinyl lnh. DTA No. mhni mhm mhm Wt. 7c Wt. 72 Wt. "7r Vise m.p f.p.

7 Recipe p.h.m.

Butadienc 100 n-Hexane 660 Diphenyl sulfide variable Lithium aluminum hydride (.45M in diethyl ether) 1.3 mhm Titanium tetrachloride 0.65 mhm Iodine 1.3 mhm Temperature. C 50 Time. hours 20 Charge Order: n-Hexane. N purge. S. LiAlH solution.

TiCl I butadiene; shortstopped with isopropyl alcohol-toluene containing 1 phr 2.6-di-t-hutyl-4-methylphenol: and coagulated with isopropyl alcohol Ex. 15 Conv. Trans Vinyl lnhv No. mhm Wt. 71 Wt. I: Wt. 71 Visc.

The above data indicated that the use of diphenyl sulfide appeared to not only suppress conversion of monomer, but also to suppress the trans content of the polymers.

EXAMPLES 44-55 A series of runs was made employing variable amounts of tetrahydrothiophene as the thioether, and also employing varying amounts of titanium tetrachlo ride. Neither molecular iodine nor titanium tetraiodide was employed.

Recipe p.h.m.

Butadiene 100 n-Hexane 660 Tctrahydrothiophene variable Lithium aluminum hydride (0.36M in diethyl ether) 2.0 mhm Titanium tetrachloride variable Temperature. C 50 Time. hours 24 Charge Order: n-l-lexane. N purge, tctrahydrothiophene.

LiAlH solution. TiCL. butadiene. 50C

olymerization Ex. TiCl Conv. Trans Vinyl lnh. No. mhm mhm Wt. 71 Wt. 7t Wt. 71 Visc 44 0.5 O 2 45 0.5 l 6 46 0.5 l l 47 0.5 36 8.7 62.8 1.09 48 1.0 O 3 46.1 38.4 49 1.0 l 14 50 1.0 5 27 51 L0 10 32 10.4 60.8 0.77 52 2.0 (J O 53 2.0 l 0 54 2.0 5 0 55 2.0 10 trace The absence of molecular iodine apparently caused poor conversion and poor trans values under condiexcessive amounts of titanium tetrachloride in proportion to the amount of lithium aluminum hydride present.

What is claimed is: l. A method for polymerizing 1,3-butadiene to produce high trans-polybutadiene comprising:

contacting 1,3-butadiene under polymerization conditions with a catalyst comprising three components; wherein the first component of said catalyst is an oxyether solution of LiAll-L; wherein the second component of said catalyst is a titanium halide component selected from the group consisting of titanium tetrachloride plus molecular iodine, titanium tetrabromide plus molecular iodine, and titanium tetraiodide; and wherein the third component of said catalyst is at least one thioether represented by the general formula .R-s-R' wherein R and R are hydrocarbon radicals selected from the group consisting of alkyl and cycloalkyl radicals containing from about 1 to 12 carbon atoms, or R and R' are hydrocarbon radicals selected from the group consisting of alkylene groups joined to the sulfur atom and to each other to form a saturated heterocyclic thioether containing from about 4 to 10 carbon atoms.

2. The method of claim 1 wherein the mole ratio of thioether to LiAlH is in the range of from about 0.1 :1 to 100:1; wherein the mole ratio of LiAll-L, to the titanium halide component is in the range of from about 1:1 to 6:1; and wherein the mole ratio of molecular iodine to titanium tetrachloride and titanium tetrabromide is in the range of from about 0.531 to 5:1.

3. The method of claim 2 wherein the mole ratio of thioether to LiAll-L, is in the range of from about 1:1 to 50:1; wherein the mole ratio of LiAll-L, to the titanium halide component is in the range of from about 1.521 to 5:1; and wherein the mole ratio of molecular iodine to titanium tetrachloride and titanium tetrabromide is in the range of from about 1:1 to 3 :1.

4. The method of claim 1 wherein said polymerization is carried out in the presence of a diluent selected from the group consisting of paraffin and cycloparaffin hydrocarbons and mixtures thereof;

wherein the polymerization temperature is in the range of from about 0 to 100C; and

wherein the polymerization pressure is sufficient to maintain the reaction mixture substantially in the liquid phase.

5. The method of claim 4 wherein the diluent is nhexane, the oxyether is diethyl ether, the titanium halide is titanium tetrachloride plus molecular iodine, and the thioether is dimethyl sulfide.

6. The method of claim 5 wherein the trans content of the trans-polybutadiene is in the range of from about to 99 percent and the conversion is in the range of from about 50 to 99 percent. 

1. A METHOD FOR POLYMERIZING 1,3-BUTADIENE TO PRODUCE HIGH TRAS-POLYBUTADIENE COMPRISING: CONTACT 1,3-BUTADIENE UNDER POLYMERIZATION CONDITIONS WITH A CATALYST COMPRISING THREE COMPONENTS; WHEREIN THE FIRST COMPONENT OF SAID CATALYST IS AN OXYETHER SOLUTION OF LIALH4; WHEREIN THE SECOND COMPONENT OF SAID CATALYST IS A TITANIUM HALIDE COMPONENT SELECTED FROM THE GROUP CONSISTING OF TITANIUM TETRACHLORIDE PLUS MOLECULAR IODINE, TITANIUM TETRABROMIDE PLUS MOLECULAR IODINE, AND TITANIUM TETRAIODIDE; AND WHEREIN THE THIRD COMPONENT OF SAID CATALYST IS AT LEAST ONE THIOETHER REPRESENTED BY THE GENERAL FORMULA
 2. The method of claim 1 wherein the mole ratio of thioether to LiAlH4 is in the range of from about 0.1:1 to 100:1; wherein the mole ratio of LiAlH4 to the titanium halide component is in the range of from about 1:1 to 6:1; and wherein the mole ratio of molecular iodine to titanium tetrachloride and titanium tetrabromide is in the range of from about 0.5:1 to 5:l.
 3. The method of claim 2 wherein the mole ratio of thioether to LiAlH4 is in the range of from about 1:1 to 50:1; wherein the mole ratio of LiAlH4 to the titanium halide component is in the range of from about 1.5:1 to 5:1; and wherein the mole ratio of molecular iodine to titanium tetrachloride and titanium tetrabromide is in the range of from about 1:1 to 3:1.
 4. The method of claim 1 wherein said polymerization is carried out in the presence of a diluent selected from the group consisting of paraffin and cycloparaffin hydrocarbons and mixtures thereof; wherein the polymerization temperature is in the range of from about 0* to 100*C; and wherein the polymerization pressure is sufficient to maintain the reaction mixture substantially in the liquid phase.
 5. The method of claim 4 wherein the diluent is n-hexane, the oxyether is diethyl ether, the titanium halide is titanium tetrachloride plus molecular iodine, and the thioether is dimethyl sulfide.
 6. The method of claim 5 wherein the trans content of the trans-polybutadiene is in the range of from about 80 to 99 percent and the conversion is in the range of from about 50 to 99 percent. 